When a liquid processing such as, for example, a chemical liquid processing or a rinse processing, is performed on a semiconductor wafer (hereinafter, referred to as a “wafer”) that is a substrate, a processing liquid nozzle held by a nozzle arm is positioned above the wafer so as to supply a processing liquid. However, the processing liquid supplied from the processing liquid nozzle may be attached to the nozzle arm due to, for example, rebound from the wafer. When the processing liquid is dried, it may cause occurrence of particles.
Japanese Patent Laid-Open Publication No. 2013-26369 discloses a shower nozzle in which a plurality of injection holes for injecting a cleaning liquid are formed side by side along a direction where a nozzle arm extends, and injects the cleaning liquid toward the nozzle arm so as to perform cleaning (see, e.g., paragraphs 0056 to 0057 and 0081, and FIG. 3). However, it is difficult to supply the cleaning liquid to a surface of the nozzle am which does not face the ejection holes. Thus, some portion may be left uncleaned.